title: Electrophysiological intermediate biomarkers for oxidative stress in schizophrenia.
abstract: OBJECTIVE
  Diverse electrophysiological abnormalities have been associated with schizophrenia, but the underlying causes remain elusive. We tested whether the altered oxidative stress in schizophrenia contributes to the electrophysiological abnormalities.
  
  
  METHODS
  We used an auditory oddball task to measure mismatch negativity (MMN) and gamma band response on 29 schizophrenia patients and 25 normal controls. Oxidative stress was assessed by monomeric glutathione (GSH, reduced form) and glutathione disulfide (GSSG, oxidized form).
  
  
  RESULTS
  Patients had reduced MMN (p=0.015) and reduced power of gamma band responses at 21-40 Hz and 41-85 Hz (all p<0.001). GSH was significantly lower (p<0.001) while %GSSG was higher (p=0.023) in patients compared with controls. MMN was correlated with GSH in controls; while 21-40 Hz responses were correlated with GSH in patients. Lower GSH and higher GSSG levels were associated with low community functioning (p=0.018). Multivariate mediation modeling showed that gamma band at 21-40 Hz was a significant mediator for GSH effect on community functions.
  
  
  CONCLUSIONS
  High beta/low gamma range (21-40 Hz) responses may be an intermediate biomarker indexing oxidative stress and its effect on clinical functions.
  
  
  CONCLUSIONS
  Electrophysiological abnormalities and associated clinical functional changes may in part be associated with heightened oxidative stress in schizophrenia.
authors.affiliation: Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland, School of Medicine, Baltimore, MD, United States; Hospital Clínico de Salamanca, Department of Psychiatry, Salamanca, Spain.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Ballesteros
authors.forename: Ann
authors.initials: A
authors.lastname: Summerfelt
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Du
authors.forename: Pan
authors.initials: P
authors.lastname: Jiang
authors.forename: Joshua
authors.initials: J
authors.lastname: Chiappelli
authors.forename: Malle
authors.initials: M
authors.lastname: Tagamets
authors.forename: Patricio
authors.initials: P
authors.lastname: O'Donnell
authors.forename: Peter
authors.initials: P
authors.lastname: Kochunov
authors.forename: L Elliot
authors.initials: LE
authors.lastname: Hong
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D015415:Biomarkers / Q000097:blood; D005071:Evoked Potentials; D005260:Female; D005978:Glutathione / Q000097:blood*; D019803:Glutathione Disulfide / Q000097:blood*; D006801:Humans; D008297:Male; D008954:Models, Biological; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D012559:Schizophrenia / Q000097:blood* / Q000503:physiopathology
chemical_list: D015415:Biomarkers; D005978:Glutathione; D019803:Glutathione Disulfide
keywords: GSH; GSSG; MMN; Oscillations; Oxidation; Schizophrenia